Jacot T A, Striker G E, Stetler-Stevenson M, Striker L J
Renal Cell Biology Section, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
Lab Invest. 1996 Dec;75(6):791-9.
Mice transgenic for bovine growth hormone (bGH) develop progressive mesangial sclerosis resulting in uremia. Mesangial cells from bGH mice were isolated to determine whether the cells maintained a stable phenotypic change in the synthesis and degradation of extracellular matrix, which contribute to the glomerular lesions in vivo. The bGH mesangial cells were 1.2-fold larger than cells from control mice. They had a 1.7-fold increase in doubling time, a 7-fold decrease in labeling index (p < 0.0001), and a 2.4- and 2-fold decrease in c-myc (p < 0.05) and insulin-like growth factor I gene expression, respectively. Collagen synthesis and degradation were studied by PCR, ELISA, and gelatin zymography. bGH mesangial cell alpha 1 collagen IV mRNA levels were increased 2.3-fold (0.47 +/- 0.25 versus 0.20 +/- 0.09 attomoles/500 cells, p < 0.01) whereas secreted collagen IV and collagen IV in the cell lysates were increased 1.4-fold (25.1 +/- 5 versus 17.2 +/- 4 ng/ml/10(5) cells) and 1.8-fold (30.5 +/- 3 versus 16.7 +/- 3 ng/ml/10(5), p < 0.05), respectively. There were no differences in collagen I mRNA levels or in the protein content of either the media or cell lysates. We were not able to detect metalloproteinase 9 (MMP-9) mRNA expression or MMP-9 protein in bGH mesangial cell medium, whereas both mRNA and protein were present in controls. MMP-2 mRNA and enzyme activity in bGH cells were, however, elevated 1.5-fold (p < 0.05) and 2.1-fold (p = 0.05) over controls. Transforming growth factor beta 1 mRNA in bGH cells was 1.6-fold higher than that of controls (p < 0.05). The data suggest that (a) mesangial lesions may result from stable, genetically induced, phenotypic changes in mesangial cells, and (b) alterations of MMP-9 and collagen IV expression by mesangial cells may contribute to an imbalance between extracellular matrix synthesis and degradation and play a critical role in the genesis of glomerulosclerosis.
转牛生长激素（bGH）基因的小鼠会发生进行性系膜硬化，最终导致尿毒症。分离bGH小鼠的系膜细胞，以确定这些细胞在细胞外基质合成和降解方面是否维持稳定的表型变化，而细胞外基质的合成和降解在体内会导致肾小球病变。bGH系膜细胞比对照小鼠的细胞大1.2倍。它们的倍增时间增加了1.7倍，标记指数降低了7倍（p<0.0001），c-myc和胰岛素样生长因子I基因表达分别降低了2.4倍和2倍（p<0.05）。通过PCR、ELISA和明胶酶谱法研究了胶原蛋白的合成和降解。bGH系膜细胞α1胶原蛋白IV mRNA水平增加了2.3倍（0.47±0.25对0.20±0.09阿托摩尔/500个细胞，p<0.01），而细胞裂解液中分泌的胶原蛋白IV和胶原蛋白IV分别增加了1.4倍（25.1±5对17.2±4 ng/ml/10(5)个细胞）和1.8倍（30.5±3对16.7±3 ng/ml/10(5)，p<0.05）。胶原蛋白I mRNA水平以及培养基或细胞裂解液中的蛋白质含量均无差异。我们未能在bGH系膜细胞培养基中检测到金属蛋白酶9（MMP-9）mRNA表达或MMP-9蛋白，而对照中同时存在mRNA和蛋白。然而，bGH细胞中的MMP-2 mRNA和酶活性比对照分别升高了1.5倍（p<0.05）和2.1倍（p = 0.05）。bGH细胞中的转化生长因子β1 mRNA比对照高1.6倍（p<0.05）。数据表明：（a）系膜病变可能源于系膜细胞中稳定的、基因诱导的表型变化；（b）系膜细胞中MMP-9和胶原蛋白IV表达的改变可能导致细胞外基质合成与降解失衡，并在肾小球硬化的发生中起关键作用。
